Gas generating solid propellant containing 5-aminotetrazole nitrate

ABSTRACT

A GAS GENERATING SOLID COMPOSITE PROPELLANT COMPOSITION COMPRISING 5-AMINOTETRAZOLE NITRATE AS THE OXIDANT COMPONENT.

United States Patent O Int. Cl. C06d /06 US. Cl. l49-19 7 Claims ABSTRACT OF THE DISCLOSURE A gas generating solid composite propellant composition comprising S-aminotetrazole nitrate as the oxidant component.

BACKGROUND OF THE INVENTION This invention relates generally to composite propellants and more particularly to composite propellant compositions especially useful as gas generators.

In the past, the mainstay of gas generating composite propellants has been based on ammonium nitrate as the oxidizing component. Although generally acceptable for the most part, the ammonium nitrate based gas generators burn very slowly, i.e., about 0.10 inch/sec. even with the addition of burning rate modifiers. Consequently, large volumes of gas are not produced quickly by these systems and therefore they are not effective for purposes where total pressure is required immediately, for instance where the guidance of a missile is dependent upon instantaneous total pressurization. Efforts have been made to improve the burning rates of ammonium nitrate gas generators but have not been totally successful, since the addition of burning rate modifiers, while increasing the burning rate, cause additional problems, such as the erosion of hardware due to the formation of metal oxides not otherwise present in the system. However, a desirable characteristic of the ammonium nitrate compositions, also desirable for all gas generators, is its low flame temperature.

Another gas generating propellant composition which has been employed in the past is based upon ammonium perchlorate (AP) as the oxidant. Although these have higher burning rate characteristics than the ammonium nitrate based compositions, the AP generators yield deleterious corrosive gases and therefore also have limited applicability.

SUMMARY OF THE INVENTION Accordingly, it is one object of this invention to provide a novel gas generating composite propellant composition.

Another object of this invention is to provide a gas generating composite propellant which is faster burning than the ammonium nitrate based gas generators and has a comparable low flame temperature.

Still another object of this invention is to provide a gas generating composite propellant which only yields noncorrosive gases upon combustion.

These and other objects are achieved herein by providing a gas generating composite propellant composition comprised of S-aminotetrazole nitrate as the oxidizing component.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The gas generating propellant compositions of this invention are based upon S-aminotetrazole nitrate, depicted by structural Formula I below as the oxidizing material.

3,734,789 Patented May 22, 1973 II N C-NHa-HNOa Formula I The oxidizer of Formula I may be incorporated into any compatible conventional binder matrix material. Among these are, for example, polybutadienes with carboxyl functionality such as Butarez CTL I which is a mixture of carboxyl-terminated polybutadiene and non-functional polybutadiene, and a product of the Phillips Petroleum Company, Bartlesville, Okla., and Butarez CTL H, which is a carboxyl-terminated polybutadiene and also a product of the Phillips Petroleum Company; polybutadienes having hydroxyl group functionality, polybutadienes having epoxy functionality, polybutadienes having amino group functionality, and polybutadienes having isocyanate group functionality; polyethers and polyesters having hydroxyl group functionality and other glycidyl ether epoxy resins. The molecular weights of the binder materials used in accordance with this invention are not critical and may vary depending upon particular mechanical properties which may be desired. Other binder matrices which are also operable herein are the moldable materials such as the gum rubbers of polyisoprene, butyl rubber and the like. Obviously, in the preparation of the gas generating composite propellants of this invention any appropriate compatible curing agent is employed when required for this purpose. Among such curing agents which are operable herein are for example, the isocyanates, such as toluene diisocyanate (TDI), the epoxy resins such as Epon 812, Epon 801, both products of the Shell Chemical Corporation, Emeryville, Calif, Epotuf STF6, a product of Reichold Chemical, Inc., New York Der 332, a product of the Dow Chemical Company, aziridines such as methylaziridinyl phosphine oxide (MAPO) and other such as p-quinone dioxime (GMF). For vulcanization purposes of the gum rubbers employed, sulfur and sulfur containing compounds are utilized. Moreover, any of the conventional curing catalysts such as ferric actylacetonate (FeAA) or other iron, cobalt of chromium containing compounds may also be utilized.

A number of other materials may also be added to the gas generators of the present invention such as coolants to lower the fiame temperature like ammonium oxalate, oxamide and guanidine nitrate, metal fuels such as aluminum and boron, plasticizers such as dioctyladipate, COnco oil (an aromatic hydrocarbon, made by the Continental Oil Company, New York, N.Y.), Circolight oil (another aromatic hydrocarbon made by the Sun Oil Company of Philadelphia, Pa.), wetting agents, burning rate modifiers and other ballistic modifiers. However, it should be recognized that one of the advantages of the present gas gene'rating systems is the absence of corrosive gases and erosive metal oxides upon combustion and therefore the addition of some of these other materials to the basic S-aminotetrazole nitrate and binder composition may act to diminish this advantageous characteristic to some extent.

The S-aminotetrazole nitrate oxidant is present in the compositions of this invention in amounts within the range of from about 50 to about percent by weight of the total composition, while the binder material (including the curing agent, if employed) is present in amounts within the range of from about 10 to about 50 percent by weight. Preferably, the oxidant and the binder material are present in about stoichiometric quantities to effect complete carbon combustion. Other additives which may be desired as hereinabove described should not be included in amounts greater than about 20 percent by weight.

Having generally described the invention the following examples are given for purposes of illustration. It will be understood that the invention is not limited to these examples, but is susceptible to different modifications that will be recognized by one of ordinary skill in he art.

EXAMPLE I.-Composition Component: Percent weight S-aminotetrazole nitrate 74.6

R-45M(a hydroxyl-terminated polybutadiene, mo-

lecular weight 2600, OH functionality 2.4, a product of Sinclair Petrochemicals New York,

N.Y.) 18.6 Conco oil 5.0 FeAA 0.03 Lecithin (wetting agent) 0.1 Toluene diisocyanate 1.4

The composition of Example I was prepared using conventional propellant mixing procedures. Conventional strand burning testing techniques indicates the composition of Example I has a burning rate of 0.38 inch/sec. at 70 F. and 1000 p.s.i.

EXAMPLE II.-Composition p-Quinone dioxime The composition of Example II was compression molded and has a density of .056 lbs./cu. in. Upon strand burning tests the composition has a burning rate 0.57 inch/sec. at 77 F. and 1000 p.s.i.

The gas generating compositions made in accordance with this invention may be used, for instance, for actuating gas pressure operated mechanical devices, e.g., for driving engines, electric generator motors, and turbines or for operating pneumatic tools, and for propulsion and guidance of rockets or other gas escape reaction propelled devices.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A gas generating solid propellant composition comprising from about 50 to about 90 percent by weight of the total composition of S-aminotetrazole nitrate as the oxidant and from about 10 to about 50 percent by weight of a binder matrix; wherein the total amount of said oxidant and said binder matrix in said composition is at least about percent by weight of the total composition.

2. The gas generating solid propellant composition of claim 1 wherein said binder matrix is selected from the group consisitng of a cured polybutadiene having carboxyl group functionality, a cured mixture of non-functional polybutadiene and polybutadiene having carboxyl group functionality, a cured polybutadiene having hydroxyl functionality, a cured polyether having hydroxyl group functionality, a cured polyester having hydroxyl lgroup functionality, a cured epoxy resin and a gum rub- 3. The gas generating solid propellant composition of claim 1 wherein said S-aminotetrazole and said binder matrix are present in about stoichiometric quantities so as to effect complete carbon combustion.

4. The gas generating solid propellant composition of claim 1 wherein said binder matrix is hydroxyl-terminated polybutadiene cured with an isocyanate.

5. The gas generating solid propellant composition of claim 1 wherein said binder matrix is selected from the group consisting of polyisoprene, polyisobutylene, and butyl rubber.

6. The gas generating solid propellant of claim 1 comprising 74.6 percent S-aminotetrazole nitrate and 18.6 percent of an hydroxy terminated polybutadiene as the binder matrix.

7. The gas generating solid propellant composition of claim 1 comprising percent S-aminotetrazole nitrate and 12.75 percent polyisoprene rubber as the binder matrix.

References Cited UNITED STATES PATENTS 2,480,852 9/1949 Hale et a1. l4992 X 3,171,249 3/1965 Bell 149-36 X 3,123,507 3/1964 Butts et a1. 149-19 2,557,463 l/l951 Pring l4992 3,173,921 3/1965 Einberg l4992 X 3,308,170 3/1967 Pritchett et al. 260-632 3,321,341 5/1967 Ottoson 149-l9 3,440,292 4/1969 Allen 260-633 BENJAMIN R. PADGETI, Primary Examiner E. A. MILLER, Assistant Examiner US. Cl. X.R. l4992 

